1. Field of the Invention
The invention relates to exhaust gas recirculation (EGR) systems in which significant quantities of exhaust gas are recirculated to the intake of an internal combustion engine.
2. Description of the Related Art
In the continuing quest to meet lower emissions levels for internal combustion engines, the use of ever increasing quantities of EGR has been proposed. In order to reduce the combustion temperatures and, therefore, the generation of oxides of nitrogen, percentages of up to 50% and higher have been implemented. In order to minimize the effect of the large quantities of exhaust gas recirculation, it has become necessary to significantly cool the exhaust gasses to a point that greatly increases their density and minimizes the effect on power and fuel consumption when combined with the combustion air for the engine.
One of the problems with a system of this type is that the moisture in the products of combustion reaches a point where the water condenses into droplets that can accumulate or puddle at random locations within the system. Depending upon the engine operating conditions, the random collection of droplets may be swept into the intake of one or more cylinders in an uneven manner. While the engine can function with this occurrence, it can cause excess oxides of nitrogen in some cylinders and increased smoke and hydrocarbons in other cylinders.
What is needed in the art, therefore, is an EGR system that recirculates high percentages of exhaust gas but avoids the uncontrolled ingestion of water droplets into the engine.